Massa, the Finn's team-mate from 2007-09, said: "One of the problems is here", pointing to his head.

"Everyone calls him the Iceman, but he is not really like that. He can suffer with pressure and it shows in some results."

Williams driver Massa was often in a similar situation at Ferrari when he was Fernando Alonso's team-mate from 2010-13 and said "it is not nice to be in that position".

The Brazilian believes Raikkonen "needs to relax and try to do his best because he is a big talent and he can do better than he is".

Kimi Raikkonen spun, with spectacular results, during the Canadian Grand Prix

The Finn started the season well, but has slipped backwards compared to current Ferrari team-mate Sebastian Vettel in the last four races.

He is fourth in the world championship, 48 points behind Vettel.

Raikkonen said: "I will try to do good races and see what happens. Hopefully at some point it will happen. There is always speculation this time of year and the same stories."

Ferrari's main concern had been Raikkonen's qualifying form, but two errors in the last two races have raised worries about his race performance as well.

He lost third place at the Canadian Grand Prix because of a spin and then retired from the last race in Austria following a huge crash with McLaren's Fernando Alonso, caused when Raikkonen lost control of his car under acceleration in fifth gear.

Raikkonen said the accident changed nothing for him in the build-up to the British Grand Prix at Silverstone on Sunday.

"I had accidents before and I probably will in the future," he said. "You pay the price when things go wrong."

Ferrari have not decided whether to replace Raikkonen and are to give him another few races to try to improve his performance before they make a final decision.

However, they have compiled a list of potential replacements should Raikkonen not improve.

Their number one choice is said to be Red Bull's Daniel Ricciardo, but the Australian has a contract until 2018 which is said by sources to be watertight and the former champions have said they are not interested in selling him.

Ricciardo said this week he was "flattered" to be of interest but it was "unlikely" he would move, although he could not rule it out.

Next on Ferrari's list is Force India's Nico Hulkenberg, who said on Thursday that he was considering his options for 2016.

The Italian team are also exploring the possibility of Williams's Valtteri Bottas, but have not been able to sort out a financial deal that would free him from his commitment to his current team, who have an option on the younger Finn for 2016.

Felipe Massa (left) is sixth in the world championship, 10 points behind Raikkonen